houdini/lib/calculate/calculate_fees.rb

# License: AGPL-3.0-or-later WITH Web-Template-Output-Additional-Permission-3.0-or-later
module CalculateFees
  BaseFeeRate = 0.022 # 2.2%
  PerTransaction = 30 # 30 cents

  def self.for_single_amount(amount, platform_fee=0.0)
    ParamValidation.new({fee: platform_fee, amount: amount}, {
      amount: {min: 0, is_integer: true},
      fee: {min: 0.0, is_float: true}
    })
    fee = BaseFeeRate + platform_fee
    (amount * fee).ceil.to_i + PerTransaction
  end

end